MITIGATION OF HAZARDOUS COMETS AND ASTEROIDS It is known that large asteroids and comets can collide with the Earth with severe consequences. Although the chances of a collision in a person’s lifetime are small, collisions are a random process and could occur at any time. This book collects the latest thoughts and ideas of scientists concerned with mitigating the threat of hazardous asteroids and comets. It reviews current knowledge of the population of potential colliders, including their numbers, locations, orbits, and how warning times might be improved. The structural properties and composition of their interi- ors and surfaces are reviewed, and their orbital response to the application of pulses of energy is discussed. Difficulties of operating in space near, or on the surface of, very low mass objects are examined. The book concludes with a discussion of the problems faced in communicating the nature of the impact hazard to the public. Michael Belton is Emeritus Astronomer at the National Optical Astronomy Observatory, Tucson, Arizona, and President of Belton Space Exploration Initia- tives, LLC. Thomas Morgan is a Discipline Scientist in the Office of Space Science at the National Aeronautics and Space Administration, Washington, District of Columbia. Nalin Samarasinha is an Assistant Scientist at the National Optical Astron- omy Observatory, Tucson, Arizona. Donald Yeomans manages NASA’s Near-Earth Object Program Office and JPL’s Solar System Dynamics group at the Jet Propulsion Laboratory of the Cali- fornia Institute of Technology, Pasadena, California. MITIGATION OF HAZARDOUS COMETS AND ASTEROIDS edited by MICHAEL J. S. BELTON Belton Space Exploration Initiatives, LLC THOMAS H. MORGAN National Aeronautics and Space Administration NALIN H. SAMARASINHA National Optical Astronomy Observatory DONALD K. YEOMANS JetPropulsion Laboratory, California Institute of Technology published by the press syndicate of the university of cambridge The Pitt Building, Trumpington Street, Cambridge, United Kingdom cambridge university press The Edinburgh Building, Cambridge, CB2 2RU, UK 40 West 20th Street, New York, NY 10011–4211, USA 477 Williamstown Road, Port Melbourne, VIC 3207, Australia Ruiz de Alarc´on13, 28014 Madrid, Spain Dock House, The Waterfront, Cape Town 8001, South Africa http://www.cambridge.org C Cambridge University Press 2004 This book is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 2004 Printed in the United Kingdom at the University Press, Cambridge Typeface Times 11/14 pt. System LATEX2ε [tb] A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Publication data Mitigation of hazardous impacts due to asteroids and comets / Michael J.S. Belton...[etal.], editors. p. cm. Includes bibliographical references and index. ISBN 0 521 82764 7 1. Near-earth asteroids. 2. Asteroids – Collisions with Earth – Prevention. 3. Comets – Collisions with Earth – Prevention. I. Belton, M. J. S. QB651.M57 2004 523.44 – dc22 2003065427 ISBN 0 521 82764 7 hardback The publisher has used its best endeavors to ensure that the URLs for external websites referred to in this book are correct and active at the time of going to press. However, the publisher has no responsibility for the websites and can make no guarantee that a site will remain live or that the content is or will remain appropriate. Contents List of contributors page vii Preface xi Acknowledgments xiii Glossary xiv 1 Recent progress in interpreting the nature of the near-Earth object population 1 William F. Bottke, Jr., Alessandro Morbidelli, and Robert Jedicke 2 Earth impactors: orbital characteristics and warning times 22 Steven R. Chesley and Timothy B. Spahr 3 The role of radar in predicting and preventing asteroid and comet collisions with Earth 38 Steven J. Ostro and Jon D. Giorgini 4 Interior structures for asteroids and cometary nuclei 66 Erik Asphaug 5 What we know and don’t know about surfaces of potentially hazardous small bodies 104 Clark R. Chapman 6 About deflecting asteroids and comets 113 Keith A. Holsapple 7 Scientific requirements for understanding the near-Earth asteroid population 141 Alan W. Harris 8Physical properties of comets and asteroids inferred from fireball observations 153 Mario Di Martino and Alberto Cellino 9 Mitigation technologies and their requirements 167 Christian Gritzner and Ralph Kahle v vi Contents 10 Peering inside near-Earth objects with radio tomography 201 W. Kofman and A. Safaeinili 11 Seismological investigation of asteroid and comet interiors 234 James D. Walker and Walter F. Huebner 12 Lander and penetrator science for near-Earth object mitigation studies 266 A. J. Ball, P. Lognonne,´ K. Seiferlin, M. Patzold,¨ and T. Spohn 13 Optimal interception and deflection of Earth-approaching asteroids using low-thrust electric propulsion 292 Bruce A. Conway 14 Close proximity operations at small bodies: orbiting, hovering, and hopping 313 Daniel J. Scheeres 15 Mission operations in low-gravity regolith and dust 337 Derek Sears, Melissa Franzen, Shauntae Moore, Shawn Nichols, Mikhail Kareev, and Paul Benoit 16 Impacts and the public: communicating the nature of the impact hazard 353 David Morrison, Clark R. Chapman, Duncan Steel, and Richard P. Binzel 17 Towards a national program to remove the threat of hazardous NEOs 391 Michael J. S. Belton Index 411 Contributors Erik Asphaug William F. Bottke, Jr. Earth Science Department Department of Space Studies University of California at Santa Cruz Southwest Research Institute Santa Cruz, CA 95064, USA 1050 Walnut Street Boulder, CO 80302, USA A. J. Ball Planetary and Space Sciences Research Alberto Cellino Institute INAF-Osservatorio Astronomico The Open University di Torino Walton Hall Strada Osservatorio 20 Milton Keynes, MK7 6AA, UK I-10025 Pino Torinese (TO), Italy Michael J. S. Belton Clark R. Chapman Belton Space Exploration Initiatives, Department of Space Studies LLC Southwest Research Institute 430 S. Randolph Way 1050 Walnut Street Tucson, AZ 85716, USA Boulder, CO 80302, USA Paul Benoit Arkansas–Oklahoma Center for Space Steven R. Chesley and Planetary Sciences Jet Propulsion Laboratory Chemistry and Biochemistry MS 301-150 Department 4800 Oak Grove Drive University of Arkansas Pasadena, CA 91109, USA Fayetteville, AR 72701, USA Bruce A. Conway Richard P. Binzel Department of Aeronautical and Massachusetts Institute of Technology Astronautical Engineering 54-410 306 Talbot Laboratory Cambridge, MA 02139, USA MC-236 vii viii List of contributors University of Illinois Robert Jedicke Urbana, IL 61801, USA University of Hawai’i Institute for Astronomy, Mario Di Martino 2680 Woodlawn Drive INAF-Osservatorio Astronomico Honolulu, HI 96822, USA di Torino Strada Osservatorio 20 Ralph Kahle I-10025 Pino Torinese (TO), Italy DLR Institute of Planetary Research Rutherfordstrasse 2 Melissa Franzen D-12489 Berlin, Germany Arkansas–Oklahoma Center for Space and Planetary Sciences Mikhail Kareev Chemistry and Biochemistry Arkansas–Oklahoma Center for Space Department and Planetary Sciences University of Arkansas Chemistry and Biochemistry Fayetteville, AR 72701, USA Department Jon D. Giorgini University of Arkansas Jet Propulsion Laboratory Fayetteville, AR 72701, USA MS 301-150 4800 Oak Grove Drive W. Kofman Pasadena, CA 91109, USA Laboratoire de Plan´etologie Bˆatiment D de Physique Christian Gritzner B.P. 53 Institute for Aerospace Engineering F-38041 Grenoble Cedex 9, Dresden University of Technology France D-01062 Dresden, Germany P. Lognonn´e Alan W. Harris D´epartment des Etudes Spatiales DLR Institute of Planetary Research Institut de Physique du Globe de Paris Rutherfordstrasse 2 4Avenue de Neptune D-12489 Berlin, Germany F-94100 Saint Maur des Foss´esCedex, Keith A. Holsapple France University of Washington Box 352400 Shauntae Moore Seattle, WA 98195, USA Arkansas–Oklahoma Center for Space and Planetary Sciences Walter F. Huebner Chemistry and Biochemistry Southwest Research Institute Department P. O. Drawer 28510 University of Arkansas San Antonio, TX 78228, USA Fayetteville, AR 72701, USA List of contributors ix Alessandro Morbidelli Albertus-Magnus-Platz Centre National des Recherches D-50923 K¨ola,Germany Scientifiques A. Safaeinili Observatoire de la Cˆoted’Azur Jet Propulsion Laboratory BP 4229 MS 300-319 F-06304 Nice Cedex 4, France 4800 Oak Grove Drive Thomas H. Morgan Pasadena, CA 91109, USA National Aeronautics and Space Nalin Samarasinha Administration Headquarters National Optical Astronomy Code SE Observatory 300 E Street, SW 950 North Cherry Avenue Washington, DC 20546, USA Tucson, AZ 85719, USA David Morrison Daniel J. Scheeres National Aeronautics and space Department of Aerospace Engineering Administration The University of Michigan Ames Research Center Ann Arbor, MI 48109, USA MS 200-7 Derek Sears Moffett Field, CA 94035, USA Arkansas–Oklahoma Center for Space Shawn Nichols and Planetary Sciences Arkansas–Oklahoma Center Chemistry and Biochemistry for Space and Planetary Department Sciences University of Arkansas Chemistry and Biochemistry Fayetteville, AR 72701, USA Department K. Seiferlin University of Arkansas Institut f¨urPlanetologie Fayetteville Westf¨alischeWilhelms-Universit¨at AR 72701, USA M¨unster Steven J. Ostro Wilhelm-Klemm-Straße 10 Jet Propulsion Laboratory D-48149 M¨unster, Germany MS 300-233 Timothy B. Spahr 4800 Oak